Rendering questions - how to affix battens, how to get scoop

[ToolbeltDandy]

I've got a few rendering questions pertaining to:

a) battens, b) scoops and c) white deposits exuding from brickwork

a) How ought I to affix the battens to the walls? Am I correct that they will be covered by the topcoat of the render and left in place?

I'm unable to find 10mm thick battens on the B&Q website (a search for battens produces one result which is 17mm thick). The search function of their website has been woeful for as long as I can remember. Does anyone know whether they stock suitable battens?

b) Will a scoop like this suffice in place of a scoop like this? I don't know where to find such a scoop in the UK.

c) What is this white exudate? It does not appear on all the brickwork.

 

[ToolbeltDandy]

Well, to answer my own questions:

a) 17 mm is a bit deep. I did manage to find some 12mm deep battens and will use those. One source says to nail the battens on which I'd have thought could damage the wall but I don't know any better so I'll follow it. The same source advised removing the battens after filling the space between them and then filling the spaces in which the battens were.

This does make me wonder, d) without the battens, how does one apply an even second coat, if there are no battens in place.

b) I wont use a scoop. Although it has been suggested that throwing the render onto the wall with a scoop will force more air out of the interface between the render and brick, many other sources ignore this completely.

c) The exudate may be lime. I don't know whether it will be a problem, but since I later plan to whitewash the wall in any case, I doubt that it will.

Finally, e) given that (I think) I want a sandy looking finish (like the lower of the examples given in this image), will I need to use a textured polyurethane float for the final coat? I don't imagine much difference in texture between a smooth wooden and a smooth steel float, but I'm only guessing.

 

[stevethespreader]

Well, to answer my own questions:

a) 17 mm is a bit deep. I did manage to find some 12mm deep battens and will use those. One source says to nail the battens on which I'd have thought could damage the wall but I don't know any better so I'll follow it. The same source advised removing the battens after filling the space between them and then filling the spaces in which the battens were.

This does make me wonder, d) without the battens, how does one apply an even second coat, if there are no battens in place.

b) I wont use a scoop. Although it has been suggested that throwing the render onto the wall with a scoop will force more air out of the interface between the render and brick, many other sources ignore this completely.

c) The exudate may be lime. I don't know whether it will be a problem, but since I later plan to whitewash the wall in any case, I doubt that it will.

Finally, e) given that (I think) I want a sandy looking finish (like the lower of the examples given in this image), will I need to use a textured polyurethane float for the final coat? I don't imagine much difference in texture between a smooth wooden and a smooth steel float, but I'm only guessing.

leave the batons in until you have put the second coat on(first coat tight scratch coat) then take out and fill .
apply with hawk and trowel you could use a stop bead as a baton also b&q do an 11mm beading you might be able to use, and if you want a finish like the one you picked out in the pics stippling the render with a stiff brush will give it a similar effect, ither that or use a texture paint after you have smooth rendered

"edit" you may want to rake those bed joints back for a better key

 

[1john]

If you leave the attens there then they will expand and contract and brack the top coat, no matter if they are in the scratch or top coat! If you screw them on then they will be easirt to remove and easier to pack out should you need to true up the wall.

I would imagine the top coat goes on a little like skimming multi-finish and battens wouldn't be required.

door jamb is about 10mm deep.

 

[ToolbeltDandy]

So I've got one for keeping the battens in place during the second coat, and another for removing them. If I were to keep them in place, then I suppose I would want to apply say 6 or 7 mm of scratch coat and then bring the render flush with the battens during the second coat? And then when I remove the battens after the second coat, I do a little jig and fill in the gaps entirely with second coat render (5:1:1)? Or should I fill in the gaps in two separate coats.

Online resources appear to be pretty vague about this. :/

"edit" you may want to rake those bed joints back for a better key

How deep? Wont PVA suffice to improve key?

 

[stevethespreader]

So I've got one for keeping the battens in place during the second coat, and another for removing them. If I were to keep them in place, then I suppose I would want to apply say 6 or 7 mm of scratch coat and then bring the render flush with the battens during the second coat? And then when I remove the battens after the second coat, I do a little jig and fill in the gaps entirely with second coat render (5:1:1)? Or should I fill in the gaps in two separate coats.

Online resources appear to be pretty vague about this. :/

"edit" you may want to rake those bed joints back for a better key

How deep? Wont PVA suffice to improve key?

if u remove your batons b4 the second coat what are you going to rule off off?, it would have been a waste of time putting them there in the first place, the scratch coat should be tight and as straight as you can get it, and yes fill in the gaps entirely with the second coat, and don't use pva as that will kill the suction, as i said to do a nice job rake the bed joints back to improve the key once you have ruled it off let it pick up and consolidate it with a float rubbing in circles then you can either stipple it or leave it plain faced the choice is yours then you can do your little jig

 

[ToolbeltDandy]

once you have ruled it off let it pick up and consolidate it with a float rubbing in circles

Hey, I understand everything that you said except this; what do you mean by ruling it off and then it picking up? Thanks.

 

[stevethespreader]

once you have ruled it off let it pick up and consolidate it with a float rubbing in circles

Hey, I understand everything that you said except this; what do you mean by ruling it off and then it picking up? Thanks.

the reason you will be putting beads or battens up is to get your render nice and straight to do this you will need a straight edge or feather edge,once you have applied the render to the thickness off the battens you will the run your straight edge up the battens shaving off any uneveness creating a nice level wall ideally you will have the battens spaced so far apart(ie as long as your straight edge) thus being able to rule off your render between the battens, the term let it pick up means let it stiffen up for a while before you start to rub it up otherwise it will be to soft and you wont be able to do anything.

 

[ToolbeltDandy]

Hi. Today, I removed some of the mortar using an angle grinder with a stone grinding wheel. I only attacked the horizontal mortar. Can you advise whether this is sufficiently deep (click to enlarge)?




I could also scratch the brick surfaces with the grinder, if that might help to improve the key.

 

[stevethespreader]

thats right you only need to do the bed joints the recommended depth is 15mm